High-performance absorbent structure

ABSTRACT

Disclosed is an absorbent structure having wet integrity higher than about 4.0 kN/gsm, softness higher than 8.0/J, pliability higher than about 70/N, and providing a substantially dry liquid-accepting surface after receiving a quantity of liquid. The structure includes an upper ply having an upper fluid receiving surface and a lower surface and including (i) a top stratum including synthetic matrix fibers bonded with a binder, the matrix fibers having length from about 2 to about 15 mm; (ii) a middle stratum in fluid communication with the top stratum, the middle stratum including natural fibers, superabsorbent particles and a binder; and (iii) a bottom stratum in fluid communication with the middle stratum, the bottom stratum including natural fibers and a binder. The structure also includes a lower ply in fluid communication with the upper ply, the lower ply having an upper surface and a lower surface and including at least one stratum including natural fibers, superabsorbent polymer particles, and a binder, wherein the lower surface of the upper ply has a surface area less than about 80% of the upper surface area of the lower ply.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority under 35 U.S.C. §119, based onU.S. Provisional Application Serial No. 60/116,036, filed Jan. 11, 1999,the entire disclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to high-capacity, thin and highlyconformable absorbent structures, useful in absorbent articles includingbaby diapers, adult incontinence products, sanitary napkins and thelike. More particularly, the present invention relates to absorbentstructures containing matrix fibers, binders and superabsorbentpolymers, the structure having an x-directional fluid storage profile.

BACKGROUND OF THE INVENTION

[0003] Absorbent structures are important in a wide range of disposableabsorbent articles including baby diapers, adult incontinence products,sanitary napkins and the like.

[0004] These and other absorbent articles are generally provided with anabsorbent core to receive and retain body liquids. The absorbent core isusually sandwiched between a liquid pervious topsheet, whose function isto allow the passage of fluid to the core and a liquid imperviousbacksheet whose function is to contain the fluid and to prevent it frompassing through the absorbent article to the garment of the wearer ofthe absorbent article.

[0005] An absorbent core for diapers and adult incontinence padsfrequently includes fibrous batts or webs constructed of defiberized,loose, fluffed, hydrophilic, cellulosic fibers. The core may alsoinclude superabsorbent polymer (“SAP”) particles, granules, flakes orfibers (collectively “particles”).

[0006] In recent years, market demand for an increasingly thinner andmore comfortable absorbent article has increased. Such an article may beobtained by decreasing the thickness of the diaper core, by increasingthe amount of SAP particles, and by calendaring or pressing the core toreduce caliper and hence, increase density.

[0007] However, higher density cores do not absorb liquid as rapidly aslower density cores because densification of the core results in asmaller effective pore size. Accordingly, to maintain suitable liquidabsorption, it is necessary to provide a low-density layer having alarger pore size above the high-density absorbent core to increase therate of uptake of liquid discharged onto the absorbent article. Thelow-density layer is typically referred to as an acquisition layer.Multiple layer absorbent core designs involve a more complicatedmanufacturing process.

[0008] The storage layer portion of a disposable diaper for example, isgenerally formed in place, during the converting process, from loose,fluffed cellulose. Such cellulose material is generally not available inpreformed sheet form because it exhibits insufficient web strength,owing to its lack of interfiber bonding or entanglement, to be unwoundor unfestooned directly onto and handled in absorbent pad-makingequipment.

[0009] Some absorbent articles such as ultra-thin feminine napkins aregenerally produced from roll-goods based nonwoven material. Such a rollof preformed absorbent core material is unwound directly as feedstockinto the absorbent article converting equipment without thedefiberization step normally required for fluff-based products, such asdiapers and incontinence pads. The nonwoven web is typically bonded orconsolidated in a fashion that gives it sufficient strength to behandled during the converting process. Absorbent structures made fromsuch nonwoven webs may also contain SAP particles. However, theseabsorbent structures are often inefficient in cases where a demand isfor acquisition and absorption of high amounts or a surge of bodyfluids. In these cases, a single sheet absorbent material often is notsufficient to fully utilize the absorbent core because the liquid is notdistributed in the structure along the length of the absorbent core. Asa result, regions of the absorbent core remain unused.

[0010] The web consolidation mechanism used in the roll-goods approachto making preformed cores provides strength and dimensional stability tothe web. Such mechanisms include latex bonding, bonding withthermoplastic or bicomponent fibers or thermoplastic powders,hydroentanglement, needlepunching, carding or the like. However, suchbonded materials provide a relatively stiff core which often does notconform well to the shape of the human body, especially in thosesituations where there is a demand for good fit to acquire and containhigh volumes of body fluids.

[0011] Pliability and softness of the absorbent core are necessary toensure that the absorbent core can easily conform itself to the shape ofthe human body or to the shape of a component (for example anotherabsorbent ply) of the absorbent article adjacent to it. This in turnprevents the formation of gaps and channels between the absorbentarticle and the human body or between various parts of the absorbentarticle, which might otherwise cause undesired leaks in the absorbentarticle.

[0012] Integrity of the absorbent core is necessary to ensure that theabsorbent core does not deform and exhibit discontinuities during itsuse by a consumer. Such deformations and discontinuities can lead to adecrease in overall absorbency and capacity, and an increase inundesired leakages. Prior absorbent structures have been deficient inone or more of pliability, integrity, profiled absorbency and capacity.For example, a conventional (fluff pulp) core has good conformabilitybecause of its high pliability and softness but at the same time it maydisintegrate easily during use, due to its poor integrity. As anotherexample, certain bonded cores, such as airlaid cores made from cellulosefluff pulp densified to greater than 0.35 g/cc have good dry integrity,but have poor wet integrity and poor conformablity.

[0013] The absorbent materials described herein exhibit a superiorcombination of x-directional storage profile, conformability andintegrity. This combination provides improved fluid acquisition andcontainment as well as increased comfort and reduced leakage potential.Further, the improved integrity of the disclosed absorbent materialsreduces the risk of deformation of the absorbent material and betterprotects the surface of the skin of the user from exposure to liquid.

SUMMARY OF THE INVENTION

[0014] The present invention relates to an absorbent structure havingwet integrity higher than about 4.0 kN/gsm, softness higher than 8.0/J,pliability higher than about 70/N, and providing a substantially dryliquid-accepting surface after receiving a quantity of liquid. Thestructure includes an upper ply having an upper fluid receiving surfaceand a lower surface and including a top stratum including syntheticmatrix fibers bonded with a binder, the matrix fibers having length fromabout 2 to about 15 mm; a middle stratum in fluid communication with thetop stratum, the middle stratum including natural fibers, superabsorbentparticles and a binder; and a bottom stratum in fluid communication withthe middle stratum, the bottom stratum including natural fibers and abinder. The structure also includes a lower ply in fluid communicationwith the upper ply, the lower ply having an upper surface and a lowersurface and including at least one stratum including natural fibers,superabsorbent polymer particles, and a binder, wherein the lowersurface of the upper ply has a surface area less than about 80% of theupper surface area of the lower ply.

BRIEF DESCRIPTION OF THE FIGURES

[0015]FIG. 1 depicts an absorbent structure of the invention comprisingan upper absorbent ply and a lower absorbent ply.

[0016]FIG. 2 is a schematic representation of a modified clamp used in aGurley tester.

[0017]FIG. 3 depicts a schematic representation of the apparatus formeasuring softness.

DETAILED DESCRIPTION OF THE INVENTION

[0018] All references cited in this application are hereby fullyincorporated by reference. In case of conflict in terminology, thepresent disclosure controls.

[0019] The present invention includes an absorbent structure of at leasttwo plies of bonded absorbent material, wherein the plies are in fluidcommunication with each other. With reference to FIG. 1, the structureincludes: (a) a shorter, upper ply 2 having three strata 6, 8 and 10;and (b) a longer, lower absorbent ply 4. In general, the surface area ofthe bottom surface of upper ply 2 is less than 80% of the surface areaof the upper surface of lower ply 4. This arrangement has an advantageover single-ply core structures by allowing for better containment andusage of the absorbent material during use of the absorbent article bythe user.

[0020] The advantage obtained by providing a two ply structure asdescribed above, is that the fluid discharge from the human body occursmainly over the frontal 16 and central 18 region of the absorbent core.The present invention places more of the absorbent capacity in theregion where the liquid discharge insults the core. Further, the overalldensity of upper ply 2 is lower than the overall density of lower ply 4.This difference in densities allows for improved fluid acquisition andrewet performance since liquid is drawn from the upper ply to the lowerply due to the capillary tension gradient between the plies.

[0021] Both the upper ply and the lower ply contain binders and SAPparticles. In general, the upper ply contains a higher concentration ofSAP particles than the lower ply. The lower ply contains at least 30%SAP particles by weight of the lower ply. A high concentration of SAPparticles provides high absorbent capacity and liquid retention withinthe absorbent structure. On the other hand, a lower concentration of SAPparticles in the upper ply is advantageous, because gel blocking (whichwould lead to the inhibition of fluid flow downward to the lower ply) inthis part of the absorbent structure may be avoided.

[0022] In the present invention, the SAP particles may be dispersedhomogeneously within the matrix of fibers and binders. Alternatively,the SAP particles may be placed in discrete locations or zones withinthe structure. For example, the SAP particles may be placed in narrowlanes 20 along the absorbent core. The lanes of SAP particles are thenseparated by lanes of fibers 22 bonded with a binder. Such a discreteplacement of SAP particles allows for better containment of theparticles, facilitates flow of liquid in the Z-direction, because thepresence of areas with little or no SAP, and allows for easier flow andwicking of the fluid along the length of the core (x-direction). Theareas with little or no SAP particles may be additionally densified toimprove integrity and create higher capillary tension within smallerpores. Preferably, such densification takes place along the length ofthe absorbent structure. The pliability of such a material can thus bemaintained, particularly in the y-direction (across the core).

[0023] With reference to FIG. 1, a schematic cross-section of apreferred absorbent structure of the present invention is shown. Theabsorbent structure includes upper ply 2 and lower ply 4. Upper ply 2includes three strata 6, 8 and 10 and is preferably made as a unitaryairlaid structure. Upper stratum 6 is a low density acquisition layerincluding from between 50 to 99% by weight of wettable synthetic fibers,preferably from 75 to 90% synthetic fibers, the balance of the stratumbeing binder material. Due to its relatively low density, large poresize, and lower wettability than that of the layers below, top stratum 6has essentially no aqueous liquid wicking capability. Fluid is easilywicked from it downward to the more wettable and smaller-pore, higherdensity strata below. Top stratum 6 includes synthetic fibers having athickness of from 2 to 30 denier, preferably of from 6 to 15 denier. Thesynthetic fibers have a length of from 2 to 15 mm, preferably of from 4to 12 mm. Optionally, the fibers may be crimped and may have a varietyof cross-sectional shapes. Top stratum 8 of upper ply 2 has a basisweight of from 20 to 120 gsm (grams per square meter), preferably offrom 30 to 60 gsm.

[0024] Middle stratum 8 of upper ply 2 is composed predominantly ofnatural fibers and also contains SAP particles. The content of SAPparticles in this stratum is from 5 to 60% by weight of upper ply 2,preferably from 20 to 40% by weight of the upper ply. The basis weightof the middle stratum of the upper ply is from 50 to 1000 gsm (grams persquare meter), preferably from 80 to 300 gsm. The middle stratum of theupper ply may be bonded with any suitable type of binder. Preferably,the binder is a bicomponent thermoplastic fiber, present in middlestratum 8 an amount of from 1 to 15% of the basis weight of the middlestratum and preferably from 5 to 10%.

[0025] Bottom stratum 10 of upper ply 2 includes bonded, natural fibers.This layer may be for example a wet-laid cellulose tissue bonded withbinders typically used in papermaking processes. Optionally, this tissuemay also be impregnated for example with one or more heat-activatedbinders, such as bicomponent binder fibers, which would be activatedduring the web curing process and would then bond the tissue togetherwith the strata above it. The bottom stratum of the upper ply may alsobe formed during the formation of the upper ply, for example as a bondedairlaid layer. Any suitable binder may be used to bind stratum 10. If,for example, a binder fiber is employed for this purpose, it is presentin an amount of from 3 to 15% of the basis weight of bottom stratum 10,and preferably from 5 to 10%. Other binders, such as latex-based bindersor water-dispersible bonding agents used commonly in wet papermakingprocesses are also suitable. Stratum 10 has a basis weight of from 10 to200 gsm, preferably from 15 to 90 gsm.

[0026] Lower absorbent ply 4 is a bonded structure of natural fibers andSAP particles. In general, the amount (in weight %) of SAP particles inlower ply 4 is higher than the amount of SAP particles in upper ply 2.The lower ply contains from 30 to 80% SAP particles by weight, andpreferably from 40 to 60%.

[0027] Optionally, lower ply 4 may contain a top stratum 12, includingbonded natural fibers for better containment of SAP particles in thestratum 13 or strata below it. Any suitable binder can be used to bondthe structure of the lower ply. If, for example, a binder fiber is used,it is present in an amount of from 1 to 8% by weight of the lower ply,preferably from 2 to 5%.

[0028] In general, lower ply 4 has a higher overall density than theoverall density of upper ply 2. The density of the lower ply may be from0.1 to 0.35 g/cc (grams per cubic centimeter), preferably from 0.15 to0.25 g/cc. Densities higher than 0.35 g/cc are undesirable due toreduced conformability found with such dense structures. The basisweight of the lower ply may range from 100 to 1000 gsm, preferably from150 to 400 gsm.

[0029] The absorbent structure of the invention can be made by variousforming methods and by using various raw materials such as natural andsynthetic fibers, various types of SAP particles, and different kinds ofbinders, including fibers, powders or liquids.

[0030] Examples of the types of natural fibers which can be used in thepresent invention include: fluffed cellulose fibers prepared fromcotton, softwood and/or hardwood pulps, straw, keaf fibers, cellulosefibers modified by chemical, mechanical and/or thermal treatments,keratin fibers such as fibers obtained from feathers, as well asman-made staple fibers made with natural polymers such as cellulose,chitin, and keratin. Examples of suitable synthetic matrix fibersinclude polyethylene, polypropylene, polyester, including polyesterterephthalate (PET), polyamide, cellulose acetate and rayon fibers.Certain hydrophobic synthetic fibers, such as polyolefins, should besurface treated with surfactant to improve wettability.

[0031] U.S. Pat. Nos. 5,147,343; 5,378,528; 5,795,439; 5,807,916; and5,849,211, which describe various superabsorbent polymers and methods ofmanufacture are hereby incorporated by reference. Examples of the typesof SAP particles which may be used in this invention, includesuperabsorbent polymers in their particulate form such as irregulargranules, spherical particles, staple fibers and other elongatedparticles. The term “superabsorbent polymer” or “SAP” refers to anormally water-soluble polymer, which has been cross-linked. There areknown methods of making water-soluble polymers such as carboxylicpolyelectrolytes to create hydrogel-forming materials, now commonlyreferred to as superabsorbents or SAPs, and it is well known to use suchmaterials to enhance the absorbency of disposable absorbent articles.There are also known methods of crosslinking carboxylatedpolyelectrolytes to obtain superabsorbent polymers. SAP particles usefulin the practice of this invention are commercially available from anumber of manufacturers, including Dow Chemical (Midland, Mich.),Stockhausen (Greensboro, N.C.), and Chemdal (Arlington Heights, Ill.).One conventional granular superabsorbent polymer is based onpoly(acrylic acid) which has been crosslinked during polymerization withany of a number of multi-functional co-monomer crosslinking agents, asis well known in the art. Examples of multifunctional crosslinkingagents are set forth in U.S. Pat. Nos. 2,929,154; 3,224,986; 3,332,909;and 4,076,673. Other water-soluble polyelectrolyte polymers are known tobe useful for the preparation of superabsorbents by crosslinking, thesepolymers include carboxymethyl starch, carboxymethyl cellulose, chitosansalts, gelatin salts, etc. They are not, however, commonly used on acommercial scale to enhance absorbency of disposable absorbent articles,primarily due to lower absorbent efficiency or higher cost.

[0032] Examples of binders useful in the absorbent structure of thepresent invention include polymeric binders in a solid or liquid form.The term “polymeric binder” refers to any compound capable of creatinginterfiber bonds between matrix fibers to increase the integrity of theply. At the same time, the binder may optionally bind fibers and SAPparticles to each other. For example, a dispersion of natural orsynthetic elastomeric latex may be used as a binder. Examples ofsuitable latex binders are polymers and copolymers of acrylate, vinylacetate and styrene-butadiene. Thermoplastic fibers or powder, which arewell known in the art, are also commonly used to provide bonding uponheating of the absorbent structure to the melting point of thethermoplastic fiber or powder. Other binders, which can be used forstabilizing the absorbent structure of the present invention, includebonding agents used to bond cellulose fibers. These agents includepolymers dispersed in water, which are cured after application to thefibrous web and create bonds between fibers or between fibers and SAPparticles. Examples of such agents include various cationic starchderivatives and synthetic cationic polymers containing crosslinkablefunctional groups such as polyamide-polyamine epichlorohydrin adducts,cationic starch, dialdehyde starch and the like. Any combination of theabove-described polymeric binders may be used for stabilizing thestructure of the present invention. In one embodiment, the binder in theinvention is a binding fiber, which comprises less than about 10% byweight of the SAP particles. In another example of the invention, thebinder fibers comprise less than about 7% by weight of the absorbentstructure.

[0033] As used herein, “integrity” is a measure of the tensile strengthof a fibrous sheet, normalized for unit basis weight and is expressed inunits (kiloNewtons, kN) of x-directional force required to break a 1inch wide sample of the sheet per normalized basis weight of 1 gsm. Inorder to measure Wet Integrity (wet tensile strength) of an absorbentcore or a commercial absorbent product, the following procedure is used:

[0034] 1. 1 inch×4 inch samples are prepared. For samples with anobvious machine direction and cross direction, the 4-inch dimension iscut in the machine direction.

[0035] 2. Remove any removable plastic backsheet, coverstock orsynthetic acquisition material, leaving only the core.

[0036] 3. Weigh sample. Apply 0.9% saline solution, in an amount equalto twice the sample weight, to the center of the sample using pipette orspray bottle (Example: sample weighs 1.00 g. Apply 2.00 g salinesolution for total of 3.00 g).

[0037] 4. Insert sample into Tensile Tester (for example a Thwing-AlbertLT-150 Universal Materials Tester, default software settings used fortest) by placing in pressurized clamps.

[0038] 5. Start test.

[0039] 6. When test is finished, record results displayed. These resultsinclude Force at Peak, Elongation at Peak, Maximum Elongation, Energy atPeak, and Energy at Maximum.

[0040] The Wet Integrity as used herein is defined as the Force at Peakas measured by using the above procedure. The Wet Integrity of theabsorbent structures of the present invention are higher than 4.0kN/gsm, and preferably higher than 6.0 kN/gsm.

[0041] The softness of the absorbent structure is an important factorcontributing to the overall conformability of the structure. As usedherein, “softness” is the inverse of the amount of energy necessary tocompress a sheet, in this case the sheet being the absorbent structure.The greater the amount of energy necessary to compress a sheet, the lesssoft it is.

[0042] To measure softness of the core, the following procedure (amodified compression test) is used:

[0043] 1. Prepare samples by cutting three 4 inch×8 inch pieces (ifsample is a diaper, cut from the thicker section of diaper (if thicknessis not uniform). For samples with obvious machine direction and crossdirection, cut 8-inch dimension in machine direction.

[0044] 2. Allow plastic backsheet and coverstock material to remain onsample (applies to commercial diaper samples). If testing prototype coresamples, apply plastic backsheet, Exxon EMB-685 polyethylene film, tobottom of sample and coverstock, 15 gsm Avgol spunbond polypropylene, totop of sample (same size as sample, adhered with a small amount of sprayadhesive).

[0045] 3. Program modified compression test (for example, aThwing-Albert LT-150 Universal Materials Tester): Compression test usingfollowing non-default settings: Break Detection Method=%Drop/Displacement, Break Value=% Drop=50, Distance Traps=0.3 in./0.5in./0.7 in., Units: Distance/Displacement=inches; Force=grams, Testspeed=1 in./min. All other settings left at defaults.

[0046] 4. Insert sample into Tensile Tester using custom clamps asdepicted in FIG. 3. Sample is inserted on its edge, such that it will becompressed in the y-direction (4-inch direction), having 1 inch on bothedges within the custom clamps, thus leaving a 2-inch gap.

[0047] 5. Start test.

[0048] 6. When deflection exceeds 0.7 inch, push down on top pressurizedclamp to simulate a sample break and stop the test (does not affect testresults). Record results displayed. These results include Force at Peak,Deflection at Peak, Maximum Deflection, Energy at Peak, and Energy atMaximum Deflection, and Force at Distance Traps.

[0049] The value, which is used to calculate the softness, is Energy atMaximum Deflection, which is expressed in Joules. Energy of MaximumDeflection, E_(d max), is calculated according to the following formula:E_(d  max ) = ∫_(d  max )^(d  max )Fd

[0050] where E_(d max) is Energy at Maximum Deflection, F is force atgiven deflection, d, and d min and d max are the deflections at thestart of the test and at the end of the test, respectively.

[0051] Softness, S, is defined here according to the following formula:

S=1/(Energy at Maximum Deflection).

[0052] The result, S, is expressed here in 1 per Joule, 1/J.

[0053] In general, Softness of the overall absorbent structure of thepresent invention should be higher than 8.0/J, preferably higher than15/J.

[0054] The pliability of the absorbent structure is also an importantfactor contributing to the overall conformability of the sheet. As usedherein, “pliability” is the inverse of the amount of force necessary tobend a sheet, in this case the sheet being the absorbent structure ofthe invention. The greater the force necessary to bend the sheet, theless pliable the sheet is.

[0055] Pliability can be measured by the following procedure, using aGurley tester (Model 4171, Gurley Precision Instruments, Trey, N.Y.).

[0056] 1. Cut sample to 1 inch×3.25 inch as accurately as possible. Ifthere is a definite machine direction and cross direction, cut onesample in each direction and test each.

[0057] 2. Fit custom clamp as shown in FIG. 3, over the original clampprovided with the Gurley tester, and tighten smaller, upper thumbscrewsto secure (see FIG. 2 illustrating the custom clamp for higher basisweight, lofty sheets). The custom clamp was designed in such a way thatit does not change the thickness of the tested material, where thematerial is inserted into the clamp. If the thickness is changed as aresult of clamping then the properties of the structure are changed andthe results obtained by using the Gurley tester are affected. In thepresent method, the clamp of FIG. 3 is used to eliminate such undesiredeffects.

[0058] 3. Open the custom clamp adjustable plate by loosening longer,lower thumbscrews. Place sample in clamp by sliding sample up until itjust contacts original clamp. There should be 2.0 inches of samplecontained in the custom clamp.

[0059] 4. Adjust height of custom clamp by loosening height adjustmentscrew on original clamp. Adjust height so that a gap of 1.0 inch existsbetween the point where the sample exits the custom clamp and the pointwhere the sample will contact the lever arm.

[0060] 5. Ensure that the remaining 0.25 inch of sample extends belowthe top of the lever arm. Ensure that lever arm is not moving. Pressmotor button to move sample towards lever arm. Continue pressing motorbutton until sample clears lever arm. While doing this, observe and notethe highest number reached on the scale. Repeat this in the oppositedirection.

[0061] 6. Average the two values obtained. In the conversion chart onthe apparatus, find the factor for a 1 inch wide×1.5 inch long sampledepending on the weight used and the distance the weight was placed fromthe center on the lever arm. A 1.0 inch×3.25 inch sample tested usingthe custom clamp corresponds to a 1.0 inch×1.5 inch sample testedwithout using the custom clamp. Without the custom clamp, 0.25 inch ofsample is in the original clamp, 0.25 inch extends below the top of thelever arm, and 1 inch is the gap between. Using the custom clamp, thesame 0.25-inch number in the custom clamp is used; the other 1.75-inchin the custom clamp secures the thicker sample in place. The same0.25-inch extends below the top of the lever arm and the same one-inchgap is in between.

[0062] 7. Multiply the average reading on the scale by the appropriateconversion factor found on the chart.

[0063] The result is Stiffness, which is expressed in milligrams force,mg. Pliability, P, is defined here according to the following formula:

P=10⁶/9.81*Stiffness.

[0064] The result, P, is expressed here in 1 per Newton, 1/N. Ingeneral, Pliability of the entire absorbent structure of the presentinvention is higher than 60/N, preferably higher than 80/N.

[0065] In the present invention, high levels of softness, pliability andwet integrity have been achieved by applying one or a combination of thefollowing features in the preparation of an absorbent structure: byusing soft fibers, curled or crimped fibers, by applying soft bindersystems, such as for example fine or crimped binding fibers, elasticlatex binders or water-soluble bonding agents, by minimizing the amountsof binder, applying relatively low pressure during compaction beforecuring, and using relatively low pressure during the calandering of thesheet after it has been cured. In general, the density of the sheetafter compaction and/or calandering in the absorbent structures of theinvention should be lower than 0.35 g/cc, and preferably lower than 0.3g/cc.

[0066] In one embodiment of the invention, no carrier tissue sheet isused in the web forming process. Such carrier tissue sheets are usuallyused and become an integral part of the structure. They increase thestrength of the web but increase its stiffness.

[0067] In another embodiment of the invention, the amount of bindingfiber in the structure is less than 10% by weight of the structure. Inanother embodiment the amount of binding fiber is lower than 7% byweight of the structure. Typically, higher amounts of binders are usedwhich result in an absorbent structure of relatively high integrity butlow pliability.

[0068] In another embodiment of the invention the softness andpliability of the structure is achieved by mechanical treatment of theentire structure or of its component absorbent plies after formation ofthe absorbent plies. Such mechanical treatments include microcreping,passing the web through the nip between grooved rolls and the like. Ingeneral, in these procedures some of the bonds within the structure aredisrupted and, as a result, the structure becomes more conformable.

[0069] The integrity of the absorbent structure of this invention ishigher than that of a conventional core made with only fluff and SAPpowder and is sufficiently high to allow the a sheet of the core to beused in conversion. In particular, the wet integrity of the absorbentstructure of this invention is higher than that of conventional coresand of airlaid cores made without binders. In one embodiment, theabsorbent core has a wet integrity greater than 4.0 kN/gsm. In anotherembodiment, the absorbent has a wet integrity greater than 6.0 kN/gsm.In yet another embodiment, the absorbent has a wet integrity greaterthan 8.0 kN/gsm. The wet integrity of conventional cores and airlaidcores made without any binders is relatively low and is commonly below4.0 kN/gsm (see Table 1). In the conventional cores (formed in place),integrity is mainly dependent on mechanical entanglement of flufffibers. Since such a mechanical entanglement is due to in part to theamount of curl of the fibers, and this curl is lost at least to someextent when the material is wetted. The integrity of the conventionalcore is also decreased substantially in the wet state. In the case ofairlaid materials (such as described in U.S. Pat. Nos. 5,866,242 or5,916,670), which are made without any binders but are highly densified,the densified structures are held together mainly with the aid ofhydrogen bonds. However, such bonds are broken completely when thematerial is wetted and then the absorbent core becomes very weak.

[0070] The softness and pliability of the absorbent structure of thepresent invention are high enough that the material may conform easilyto the shape of the human body or to the shape of a component (forexample another absorbent layer) of the absorbent article adjacent toit. In one embodiment, the softness of the absorbent structure is higherthan 8.0/J and the pliability of the absorbent structure is higher than60/N.

[0071] To further increase the levels of softness, pliability and wetintegrity of the absorbent structure, the structure may be treated usingvarious chemical and/or mechanical processes. Without being bound by anytheory, it is believed that, for a given composition of the absorbentstructure, the desired level of softness, pliability, and wet integritycan be achieved with an appropriate ratio of bonded to unbondedstructural elements. If the number of bonds between the fibers orbetween the fibers and SAP particles is too small, then the wetintegrity of the structure is too low to achieve improved performance ofthe absorbent structure during use. When the user moves then such alow-integrity structure may not withstand mechanical stresses and mayproduce cracks and other discontinuities, leading to poor liquidcontainment and subsequent leaks. On the other hand, if the number ofbonds in the absorbent structure is too high, then pliability andsoftness are too low and the structure becomes less conformable,degrading performance due to formation of undesirable channels and gapsthrough which the liquid may freely flow and leak out of the absorbentarticle.

[0072] As exemplified below, the absorbent structure may be used incombination with a carrier such as cellulose tissue or a syntheticnonwoven. The absorbent structure may also be used in combination withother layers or structures to form an absorbent structure.

[0073] In another preferred embodiment, the upper ply of the structureis used separately as an absorbent structure. The one ply structureexhibits high wet integrity, high softness and high pliability, and canbe used in a variety of applications requiring such attributes. Examplesof such applications include disposable absorbent articles such asdisposable diapers, sanitary pads, adult incontinence products andtraining pants.

[0074] The one ply absorbent structure can be made as set forth in theexamples relating to the two-ply structures. Alternatively, the one plystructure may be made using an airlaid machine employing three formingheads. Examples using such a machine are set forth below as Examples 8to 11.

[0075] The invention is further described in the following non-limitingexamples.

[0076] In the following examples basis weights (in gsm) are set forth astargets. Actual basis weights obtained may vary by up to ±10%.

EXAMPLE 1

[0077] An absorbent structure was assembled by joining together upperply (component A1) and lower ply (component B1) described below. Bothabsorbent components were made by dry forming (or airlaying) on an M&Jpilot machine. The mechanical and absorbency properties of the structureare depicted in Tables 1, 3 and 4. The structure exhibited improvedperformance compared to the performance found with commercial structuresas described herein, due to the combination of profiled absorbency andappropriate levels of conformability and integrity.

[0078] Component A1. Two forming heads were used and they were fed withthe same composition and amount of raw materials. The product was laidon a carrier of 40 gsm Brand 6810 polyester polyethylene terephthalate)nonwoven (PGI). This material constituted the top stratum of the upperply. The basis weights and compositions of the middle stratum and of thebottom stratum were the same, the basis weight being 160 gsm and thecomposition being 56.3% HPF fluff (Buckeye Technologies Inc., Memphis,Tenn.), 37.5% Z1049 SAP (Stockhausen, Greensboro, N.C.) and 6.2% T-255,2.8 dpf (denier per fiber) thermoplastic, bicomponent binder fiber(Kosa, Salisbury, N.C.). The sheet was calandered after curing (160° C.;1 min. dwell) with minimum pressure to a thickness of 3 mm.

[0079] Component B1. The first forming head was fed with Foley Fluff(Buckeye Technologies) at 75 gsm and T-255 binder fiber (Kosa,Salisbury, N.C.) at 3 gsm. The formed layer was the middle stratum ofthe Lower Ply. The top stratum of the lower ply was formed by the secondforming head, which was fed with Foley Fluff (Buckeye Technologies) at55 gsm, T-255 binder fiber (Kosa, Salisbury, N.C.) at 12 gsm, andSXM4750 SAP (Stockhausen, Greensboro, N.C.) at 215 gsm. The product waslaid on a carrier, which was Duni Finner K1801 cellulose tissue (Duni,Kisa, Sweden). The carrier constituted the bottom stratum of the lowerply. The sheet was calandered after curing to a thickness of 2 mm.

[0080] The components were assembled by placing a 10×20 cm A1 sheet ofmaterial over one end of a 10×40 cm B1 sheet of material. Measurementswere made at the end where the A1 and B1 sections overlapped.

EXAMPLE 2

[0081] An absorbent structure was assembled by joining togetherComponents A2 and B2 described below. Both absorbent components weremade by dry forming on an M&J pilot machine. In the resultant structurecomponent A2 is the upper ply and component B2 is the lower ply. Themechanical and absorbency properties of the structure are depicted inTables 1, 3 and 4. The structure exhibited improved performance due tothe combination of profiled absorbency and appropriate levels ofconformability and integrity.

[0082] Component A2. The middle stratum of the Upper Ply was formed byfeeding the first forming head with HPF fluff (Buckeye Technologies,Memphis, Tenn.) at 40 gsm and 2.8 dpf T-255 binder fiber (Kosa,Salisbury, N.C.) at 2.5 gsm. The second head was used to form the topstratum of the upper ply. The second forming head was fed with HPF fluff(Buckeye Technologies, Memphis, Tenn.) at 100 gsm, Z1049 SAP(Stockhausen, Greensboro, N.C.) at 94 gsm, and 2.8 dpf T-255 binderfiber (Kosa, Salisbury, N.C.) at 13 gsm. The product was laid on acarrier, which was 48 gsm Licontrol™ 381002 (polypropylene) nonwoven(Jacob-Holm Industries, Soultz, France). This carrier constituted thetop stratum of the upper ply. The product was calandered after curingwith minimum pressure to a thickness of 3.0 mm.

[0083] Component B2. Two forming heads were used and they were fed withthe same composition and amount of raw materials. The product was laidon a carrier, which was Duni Finner K1801 cellulose tissue. Thecomposition of the overall component B2 having a basis weight of 378 gsmwas 34.1% Foley Fluff (Buckeye Technologies), 57.1% SXM3950 SAP(Stockhausen, Greensboro, N.C.), and 4% T-255, 2.8 dpf binder fiber(Kosa, Salisbury, N.C.); the balance of the structure was a carriertissue of 18 gsm. The sheet was calandered after curing to a thicknessof 2 mm.

EXAMPLE 3

[0084] An absorbent structure was assembled by joining togetherComponents A3 and B3 described below. Both absorbent components weremade by dry forming on a DanWeb pilot machine. In the resultantstructure Component A3 is the upper ply and Component B3 is the lowerply. The mechanical and absorbency properties of the structure aredepicted in Tables 1, 3 and 4. The structure exhibited improvedperformance due to the combination of profiled absorbency andappropriate levels of conformability and integrity.

[0085] Component A3. The first forming head was fed with Foley Fluff(Buckeye Technologies, Memphis, Tenn.) at 60 gsm and 2.8 dpf T-255binder fiber (Kosa, Salisbury, NC) at 10 gsm, to form the bottom stratumof the upper ply. The second head was used to form the middle stratum ofthe upper ply. The second head was fed with Foley Fluff at 98 gsm, SXM70SAP (Stockhausen, Greensboro, N.C.) at 62.5 gsm, and 2.8 dpf T-255binder fiber (Kosa, Salisbury, N.C.) at 19.5 gsm. The third head was fedwith Wellman 376×2 polyester fibers having thickness of 15 dpf andlength of 6 mm at 35 gsm. The top stratum of the upper ply thus formedwas sprayed with A-181 latex (Air Products, Allentown, Pa.) diluted to10% solids at 5 gsm. The sheet was calandered after curing with minimumpressure to a thickness of 4.1 mm.

[0086] Component B3. One forming head was used and it was fed with ND416fluff (Weyerhaeuser, Tacoma, Wash.) at 128 gsm, SXM70 SAP (Stockhausen,Greensboro, N.C.) at 225 gsm and 2.8 dpf T-255 binder fiber (Kosa,Salisbury, N.C.) at 22 gsm. The product was laid on a Cellutissue 3024cellulose tissue carrier. The sheet was calandered after curing to athickness of 1.9 mm.

EXAMPLE 4

[0087] An absorbent structure was assembled by joining togetherComponents A4 and B4 described below. Both absorbent components weremade by dry forming on a DanWeb pilot machine. In the resultantstructure Component A4 is the upper ply and Component B4 is the lowerply. The mechanical and absorbency properties of the structure aredepicted in Tables 1, 3 and 4. The structure exhibited improvedperformance due to the combination of profiled absorbency andappropriate levels of conformability and integrity.

[0088] Component A4. The first forming head was fed with Foley Fluff(Buckeye Technologies, Memphis, Tenn.) at 77.6 gsm and 2.8 dpf T-255binder fiber (Kosa, Salisbury, N.C.) at 12.4 gsm, forming the bottomstratum of the upper ply. The second head was used to form the middlestratum of the upper ply. The second head was fed with Foley Fluff at102 gsm, SP 1186 SAP (Stockhausen, Greensboro, N.C.) at 130 gsm, and 2.8dpf T-255 binder fiber (Kosa, Salisbury, N.C.) at 28 gsm. The third headwas fed with Wellman 376×2 polyester fibers having thickness of 15 dpfand length of 6 mm, at 42 gsm. The top stratum of the Upper Ply thusformed was sprayed with A-124 latex (Air Products, Allentown, Pa.)diluted to 10% solids at 8 gsm. The sheet was calandered after curingwith minimum pressure to a thickness of 5.7 mm.

[0089] Component B4. The first and second forming heads were fed withequal amounts of all components, that is with ND416 fluff (Weyerhaeuser,Tacoma, Wash.) at 37 gsm, SXM3950 SAP (Stockhausen, Greensboro, N.C.) at92.3 gsm and 2.8 dpf T-255 binder fiber (Kosa, Salisbury, N.C.) at 5gsm. The web thus formed became the bottom stratum of the lower ply.This stratum was laid on a Cellutissue 3024 cellulose tissue carrier.The third head was fed with ND416 fluff at 38.5 gsm and 2.8 dpf T-255binder fiber at 8.9 gsm, forming the top stratum of the lower ply. Thefinal sheet was calandered after curing to a thickness of 1.45 mm.

EXAMPLE 5

[0090] The structures of Examples 1, 2, 3 and 4 were analyzed for WetIntegrity, Softness and Pliability. The results obtained are summarizedin Table 1. In Table 1 are summarized also the results of the analysisof the absorbent cores of several commercial disposable infant diapers(samples A, B and C) and a sample of a high-density airlaid materialmade with fluff and SAP and without any binder (sample D). Determinationof basic structural parameters of the tested cores are shown in Table 2.The data in Table 1 demonstrate that the absorbent structures ofExamples 1, 2, 3 and 4 have much higher Wet Integrity than all the othertested commerical cores and much higher softness and pliability than thecore of sample D. TABLE 1 Wet Integrity, Absorbent Structure kN/gsmSoftness, 1/J Pliability, 1/N Example 1 5.2 8.9 72.9 Example 2 7.2 10.2112.0 Example 3 8.7 17.8 104.0 Example 4 7.0 10.6 105.2 Example A 0.810.1 175.5 Example B 2.6 12.9 137.8 Example C 1.5 7.4 117.7 Example D1.3 5.6 40.2

[0091] TABLE 2 Upper Lower Overall Overall Overall Upper core Lower coreAssembled core core average Upper Lower average Upper Lower averagewidth × width × surface Basis Basis Basis core core core core core corelength length area Weight Weight Weight Density Density Density % % %Sample (cm × cm) (cm × cm) (cm2) (gsm) (gsm) (gsm) (g/cc) (g/cc) (g/cc)SAP SAP SAP Example D  8 × 20 11 × 36 396 400 310 472 0.27 0.36 0.3137.0 51.0 43.0 Example C 385 759 0.14 26.7 Example B 468 617 0.25 53.5Example A 360 649 0.26 43.4 Example 1 10 × 20 10 × 40 400 360 375 5550.12 0.19 0.16 37.5 57.3 47.6 Example 2 10 × 20 10 × 40 400 297.5 360509 0.10 0.18 0.14 26.1 60.0 44.7 Example 3  9 × 20 10 × 40 400 290 390521 0.07 0.21 0.15 21.6 57.7 42.3 Example 4 10 × 20 10 × 40 400 400 331531 0.07 0.23 0.14 32.5 55.8 43.1

EXAMPLE 6

[0092] The structures made according to the procedures described inExamples 1, 2, 3, and 4 were tested for liquid acquisition properties.To evaluate the acquisition properties, the Acquisition Time wasmeasured, that is the time, for a given volume of saline solution to beabsorbed by an absorbent structure (until any free liquid disappearsfrom the surface of the absorbent).

[0093] The following method was used to measure the Acquisition Time:

[0094] 1. Condition sample in lab at 70° F. and 50% relative humidityfor 2 hours prior to testing.

[0095] 2. Prepare standard saline solution (0.9% NaCl/DI H₂O by weight).Add dye if desired.

[0096] 3. Determine insult volume and load to be used. Medium capacitysamples (most diapers of medium size (size #3)) use 3×75 ml insults and0.4-psi load. The absorbent structures described in Examples 1-4 belongto this category.

[0097] 4. If sample is formed in lab or on pilot machine (airlaid), cutto required dimensions. This is 4 inches×14 inches for samples made onthe lab pad former, 4 inch×16 inches for samples made on the pilotmachine. If sample is a commercial diaper, simply cut elastic legbandsso that diaper will lay flat. Take weight/thickness measurements of eachsample.

[0098] 5. Prepare airlaid samples by placing on plastic backsheet, ExxonEMB-685 polyethylene film, and adding coverstock material, 15 gsm Avgolspunbond polypropylene. Ensure that plastic backsheet material edgesfold up toward top of sample to protect against leakage while testing.

[0099] 6. Place sample in acquisition apparatus by placing sample onbottom plate, positioning foam piece on top of sample, placing insultring into hole in foam, and then positioning weighted top plates overfoam piece.

[0100] 7. Set timer for 20 minutes and place beside test apparatus.

[0101] 8. With stopwatch in one hand and graduate cylinder containinginsult volume in other hand, prepare to insult sample. Pour fluid intoinsult ring. Start stopwatch at moment the fluid strikes the sample.Empty fluid from cylinder as quickly as possible. Stop stopwatch whenfluid is absorbed by sample.

[0102] 9. Note time taken by sample to absorb fluid. Start 20 minutetimer as soon as fluid is absorbed by sample.

[0103] 10. After 20 minutes, repeat steps 7-9.

[0104] 11. After another 20 minutes, repeat steps 7-9. Note: If no othertests are to be done after the Acquisition test, the 20-minute intervalfollowing the third insult can be omitted. However, if another test isto be done following the Acquisition test (Rewet and Retention orDistribution), the 20-minute interval must be used and then the othertest may be started.

[0105] The following formula is used to calculate the Acquisition Rate:${{Acquisition}\quad {Rate}\quad \text{(}{ml}\text{/}s\text{)}} = \frac{{Insult}\quad {Volume}\quad ({ml})}{{Acquisition}\quad {{Time}(s)}}$

[0106] The results obtained from testing the structures of Examples 1,2, 3, and 4 are collected in Table 3. In Table 3 are summarized also theresults of the analysis of the absorbent cores of some commercial diaperarticles samples A, B and C and of another commercial diaper core,sample D, and having basic physical properties as described in Table 2.The data in Table 3 includes the results obtained from testing thestructures of Examples 1, 2, 3, and 4. The structures of these Exampleswere assembled according to the illustration in FIG. 1. The length ofthe Upper Plies in these structures was 20 cm in each case. The resultsin Table 3 indicate that absorbent structures of Examples 1, 2, 3, and 4have considerably shorter Acquisition Times than sample D. It can alsobe seen that the absorbent structures of Examples 3 and 4 have shorterAcquisition Times than those of the cores of all the tested commercialdiapers. TABLE 3 2nd 3rd 1st Acquisition Acquisition AcquisitionAbsorbent Structure Rate, ml/s Rate, ml/s Rate, ml/s Example 1 1.16 0.560.36 Example 2 1.35 0.86 0.63 Example 3 2.85 1.29 0.93 Example 4 5.562.71 1.83 Example A 2.01 1.19 0.83 Example E 2.25 1.70 1.24 Example B1.90 0.75 0.55 Example C 1.32 0.46 0.33 Example D 0.91 0.49 0.30

EXAMPLE 7

[0107] The structures made according to the procedures described inExamples 1, 2, 3 and 4 were tested for rewet. In order to evaluate therewet, the Rewet was measured, that is the amount of liquid, which canbe detected on the surface of the absorbent structure after itssaturation with a given amount of saline.

[0108] The following method was used to measure Rewet:

[0109] The Rewet and Retention Test is designed to be performedimmediately following the Acquisition Test. The Acquisition Testprocedure must be followed before starting this test. If no acquisitioninformation is needed, acquisition times do not have to be recorded,however the pattern of 3 insults separated by 20-minute intervals mustbe followed. It is imperative that the 20 minute interval has elapsedbefore starting this test. Sample/solution preparation is the same as inthe Acquisition test (See Acquisition Test document).

[0110] 1. Sample is now assumed to have been through the AcquisitionTest and left undisturbed for the final 20-minute time interval. Set atimer for 5 minutes and place beside test apparatus.

[0111] 2. Weigh stack of 10 Buckeye S-22 Blotter papers cut to samedimension as sample.

[0112] 3. Remove weight over sample, foam piece, and insult ring.

[0113] 4. Place stack of papers on sample.

[0114] 5. Replace foam piece and weights over sample. Start 5-minutetimer.

[0115] 6. At end of 5 minutes, remove weight and weigh stack of papers.

[0116] Note weight differences between wet and dries papers. The rewetis calculated according to the formula:

Rewet(g)=Weight of wet papers(g)−weight of dry papers (g)

[0117] The following formula is used to calculate the Rewet Retentionafter the third insult:${{Rewet}\quad {Retention}\quad (\%)} = \frac{{{{Vol}.\quad {of}}\quad {All}\quad {Insults}\quad ({ml})} - {\left( {{Rewet}\quad (g) \times 1\quad {ml}\text{/}g} \right) \times 100}}{{Volume}\quad {of}\quad {ALL}\quad {insults}\quad ({ml})}$

[0118] The structures of Examples 1, 2, 3, and 4 were tested for Rewetand the results are presented in Table 4. The data in Table 3 includesthe results obtained from testing the structures of Examples 1,2,3 and4. The structures of these Examples were assembled according to theillustration in FIG. 4. The length of the Upper Plies in thesestructures was 20 cm in each case. In Table 4 are summarized also theresults of the analysis of the absorbent cores of some commercial diaperarticles, samples A, B and C and of the commerical core, sample D, asdescribed in Table 2. The data in Table 4 indicate that except for theSample of Example E, had the lowest Rewet Retention value, all the othertested cores had Rewet Retention values at least 97%. TABLE 4 RewetRetention, Absorbent Structure % Example 1 97.0 Example 2 98.4 Example 399.4 Example 4 97.2 Example A 98.5 Example E 92.8 Example B 99.8 ExampleC 99.0 Example D 97.1

EXAMPLE 8

[0119] An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. Three forming heads were used to make the absorbentstructure. The product was laid on a carrier of Cellutissue 3024 havingbasis weight of 18 gsm. Prior to use, this tissue was impregnated with 4gsm bicomponent binder fiber, T-255 (Kosa Salisbury, N.C.), havingthickness of 2.8 denier per fiber. This fiber was deposited on thecarrier tissue on the DanWeb pilot machine and cured to bond thebicomponent fiber to the tissue. The purpose of this was to obtain agood adhesion of the carrier to the product formed on it. The carriertissue constituted the bottom stratum of the absorbent structure. Toconstruct the lower middle stratum, the first forming head of themachine was fed with 96 gsm ND416 fluff (Weyerhaeuser, Tacoma, WA) and115 gsm superabsorbent polymer SXM70 (Stockhausen, Greensboro, N.C.).Then, during the process, the upper middle stratum was formed by feedingthe second forming head with 62 gsm of Foley Fluff (BuckeyeTechnologies, Memphis, Tenn.), 25 gsm of superabsorbent polymer SXM70,and 12 gsm of bicomponent binder fiber, T-255. Finally, the top stratumwas formed by feeding the third forming head with 42 gsm Wellman 376X2polyester fiber, of which the thickness was 15 denier per fiber and thelength was 6 mm. The top stratum was sprayed with 6 gsm of latex A-181(Air Products, Allentown, Pa.), at a concentration of 10% solids. Thesheet was compacted to the thickness of 2.6 mm and cured.

EXAMPLE 9

[0120] An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. Three forming heads were used to make the absorbentstructure. The bottom stratum was formed by feeding the first forminghead with 83 gsm Foley Fluff and 7 gsm bicomponent binder fiber T-255,having thickness of 2.1 denier per fiber. The middle stratum was formedby feeding the second forming head with 110 gsm Foley Fluff, 130 gsmsuperabsorbent polymer SP 1186 (Stockhausen, Greensboro, N.C.) and 15gsm bicomponent binder fiber T-255, having thickness of 2.1 denier perfiber. The top stratum was formed by feeding the third forming head with42 gsm Wellman 376X2 polyester fiber, of which the thickness was 15denier per fiber and the length was 6 mm. The top stratum was sprayedwith 8 gsm latex A-181, at a concentration of 10% solids. The sheet wascompacted to the thickness of 5.2 mm and cured.

EXAMPLE 10

[0121] An absorbent structure was made by dry-forming on a DanWeb pilotmachine. The mechanical and absorbency properties of the structure aredepicted in Tables 5 and 6. The structure exhibited improved performancedue to the combination of appropriate levels of softness, pliability andwet integrity. The product was laid on a carrier, which was Cellutissue3024 having basis weight of 18 gsm. Prior to use this tissue wasimpregnated with 4 gsm of bicomponent binder fiber, T-255, havingthickness of 2.8 denier per fiber. The carrier tissue constituted thebottom stratum of the absorbent structure. In order to construct thelower middle stratum, the first forming head was fed with ND416 fluff(Weyerhaeuser, Tacoma, Wash.) at 80 gsm, and superabsorbent polymerSXM70 at 100 gsm. The upper middle stratum was formed with the secondforming head by feeding it with Foley fluff at 79 gsm and superabsorbentpolymer SXM70 at 38 gsm. The top stratum was formed with the thirdforming head with Wellman 376X2 poly(ethylene terephtalate) having thethickness of 15 denier per fiber and the length of 6 mm. This fiber wasfed at 38 gsm. The product was sprayed from the top with an aqueoussolution of Kymene 557H wet strength resin (Hercules, Willmington, Del.)at 10% solids. The target basis weight of Kymene solids on the web was 7gsm. Due to the pressure gradient resulting from the difference betweenthe higher pressure at the top stratum of the formed structure and thelower pressure under the forming wire the solution of the bonding agentcould penetrate to some extent to the strata below, so the Kymene couldbond both the top stratum and the strata below. The product wascalandered to get the thickness of 2.6 mm.

EXAMPLE 11

[0122] An absorbent core was made by dry-forming on an M&J commercialmachine with three forming heads. The product was laid on a carrier,which was Cellutissue 3024 having basis weight of 18 gsm. The bottomstratum was formed by feeding the first and the second heads with equalamounts of ND416 fluff, superabsorbent polymer SXM3950 (Stockhausen,Greensboro, N.C.) and bicomponent binder fiber T-255 having a thicknessof 2.8 denier per fiber. The composition of the bottom stratum thusformed, by total weight of this stratum, was 23.2% ND416, 48.2% SXM3950and 2.6% T-255. The middle stratum was formed by feeding the third headwith ND416 at 38.1 gsm and T-255 at 9 gsm. The product thus formed wasjoined with Licontrol 381002-48, a 48 gsm synthetic nonwoven (Jacob HolmIndustries, Soultz, France), which constituted the top stratum of thestructure. The structure was analyzed for mechanical and absorbencyproperties. The results are depicted in Tables 5 and 6. The structureexhibited improved performance due to the combination of appropriatelevels of softness, pliability and wet integrity.

EXAMPLE 12

[0123] The structures of Examples 1-4 were analyzed for Wet Integrity,Softness and Pliability. The obtained results are summarized in Table 6.In Table 6 are also given the results of the tests carried out with anumber of commercial diaper cores. The data in Table 6 indicate thatabsorbent structures of Examples 8-11 have higher Wet Integrity, higherSoftness and higher Pliability than all the other tested absorbentcores. TABLE 6 Wet Integrity, Softness, Absorbent Structure kN/gsm 1/JPliability, 1/N Example 8 6.5 30.4 272.7 Example 9 12.3 37.5 235.5Example 10 8.1 22.1 259.9 Example 11 6.5 13.1 199.6 Example A 0.8 10.1175.5 Example E 4.2 12.4 196.7 Example B 2.6 12.9 137.8 Example C 1.57.4 47.7 Example D 1.3 5.6 40.2

EXAMPLE 13

[0124] The structures made according to the procedures described inExamples 8-11 were tested for rewet according to the method describedabove in Example 7. as described. The results of the Rewet retention forthe structures of Examples 8-11 and an commercial absorbent core(Example E) are set forth in Table 7. It can be seen that the RewetRetention values of the structures of Examples 8-11 are as good orbetter than the Rewet Retention value for the commercial structure(Example E). TABLE 7 Rewet Retention, Absorbent Structure % Example 197.3 Example 2 83.3 Example 3 98.3 Example 4 99.1 Example E 84.6

[0125] TABLE 5 Overall Overall Overall Overall average average averagesurface Basis core core area Weight Density % Sample (cm2) (gsm) (g/cc)SAP Example D 398 472 0.31 43.0 Example C 385 759 0.14 26.7 Example B468 617 0.25 53.5 Example E 260 547 0.11 44.9 Example A 360 649 0.2643.4 Example 8 320 380 0.15 36.8 Example 9 320 395 0.08 32.9 Example 10320 364 0.14 37.9 Example 11 320 387 0.21 58.1

What is claimed is:
 1. An absorbent structure having wet integrityhigher than about 4.0 kN/gsm, softness higher than 8.0/J, pliabilityhigher than about 70/N, and providing a substantially dryliquid-accepting surface after receiving a quantity of liquid, saidstructure comprising: a) an upper ply having an upper fluid receivingsurface and a lower surface and comprising: i) a top stratum comprisingsynthetic matrix fibers bonded with a binder, said matrix fibers havinglength from about 2 to about 15 mm; ii) a middle stratum in fluidcommunication with the top stratum, the middle stratum including naturalfibers, superabsorbent particles and a binder; and iii) a bottom stratumin fluid communication with the middle stratum, the bottom stratumincluding natural fibers and a binder; and b) a lower ply in fluidcommunication with the upper ply, the lower ply having an upper surfaceand a lower surface and including at least one stratum including naturalfibers, superabsorbent polymer particles, and a binder, wherein thelower surface of the upper ply has a surface area less than about 80% ofthe upper surface area of the lower ply; c) the basis weight of the topstratum of the upper ply is from about 20 gsm to about 120 gsm; d) thebinder content (percent by weight) in the top stratum of the upper plyis from about 5% to about 20%; e) the basis weight of the middle stratumof the upper ply is from about 50 gsm to about 1000 gsm; f) the bindercontent percent by weight) in the middle stratum of the upper ply isfrom about 1% to about 10%; g) the basis weight of the bottom stratum ofthe upper ply is from about 10 gsm to about 150 gsm; h) the bindercontent (percent by weight) in the bottom stratum of the upper ply isfrom about 5% to about 15%; i) the superabsorbent particle content(percent by weight) in the upper ply is lower than the content ofsuperabsorbent particles in the lower ply; j) apparent density of theupper ply is lower than the apparent density of the lower ply; k) thebasis weight of the lower ply is from about 100 gsm to about 1000 gsm;l) apparent density of the lower ply is about 0.15 g/cc to about 0.25g/cc; m) the binder content (percent by weight) in the lower ply is fromabout 1% to about 8%; and n) the lower ply contains at least 30%superabsorbent particles of the basis weight of the lower ply.
 2. Theabsorbent structure of claim 1 wherein the length of the syntheticmatrix fibers is from about 4 to about 12 mm.
 3. The absorbent structureof claim 1 wherein the synthetic matrix fibers are from about 2 to about30 denier per fiber.
 4. The absorbent structure of claim 3 wherein thesynthetic matrix fibers are from about 6 to about 15 denier per fiber.5. The absorbent structure of claim 1 wherein the synthetic matrixfibers are selected from the group consisting of polyethylene,polypropylene, polyester, polyamide, cellulose acetate, rayon fibers,and mixtures thereof.
 6. The absorbent structure of claim 1 wherein thebinder is selected from the group consisting of latex binders,thermoplastic powders, thermoplastic fibers, bicomponent fibers andmixtures thereof.
 7. The absorbent structure of claim 1 wherein thebinder is selected from the group consisting of polyamide-polyamineepichlorohydrin adducts, cationic starch, dialdehyde starch, poly(vinylalcohol), chitosan and mixtures thereof.
 8. The absorbent structure ofclaim 1 wherein said natural fibers are selected from the groupconsisting of cotton, softwood pulps, hardwood pulps, straw, keaffibers, cellulose fibers modified by chemical, mechanical and/or thermaltreatments, keratin fibers, and mixtures thereof.
 9. The absorbentstructure of claim 1 wherein the basis weight of the top stratum of theupper ply is from about 30 gsm to about 60 gsm.
 10. The absorbentstructure of claim 1 wherein the content of synthetic matrix fibers inthe top stratum of the upper ply is from about 50 to about 99% byweight.
 11. The absorbent structure of claim 10 wherein the content ofsynthetic matrix fibers in the top stratum of the upper ply is fromabout 75 to about 90% by weight.
 12. The absorbent structure of claim 1wherein the basis weight of the middle stratum of the upper ply is fromabout 80 gsm to about 300 gsm.
 13. The absorbent structure of claim 1wherein the content of superabsorbent polymer particles in the middlestratum of the upper ply is from about 5 to about 60% by weight of theupper ply.
 14. The absorbent structure of claim 13 wherein the contentof superabsorbent polymer particles in the middle stratum of the upperply is from about 20 to about 50% by weight.
 15. The absorbent structureof claim 1 wherein the bottom stratum of the upper ply is an airlaidlayer.
 16. The absorbent structure of claim 1 wherein the bottom stratumof the upper ply is a wet-laid cellulose tissue.
 17. The absorbentstructure of claim 1 wherein the apparent density of the lower ply isfrom about 0.15 g/cc to about 0.25 g/cc.
 18. The absorbent structure ofclaim 1 wherein the basis weight of the lower ply is from about 150 gsmto about 400 gsm.
 19. The absorbent structure of claim 1 wherein thecontent of superabsorbent polymer particles in the lower ply is fromabout 30 to about 80% by weight.
 20. The absorbent structure of claim 19wherein the content of superabsorbent polymer particles in the lower plyis from about 40 to about 60% by weight.
 21. The absorbent structure ofclaim 1 wherein all layers of each ply are fully integrated in theforming process.
 22. The absorbent structure of claim 1 wherein each plyis airlaid.
 23. The structure of claim 1 wherein superabsorbent polymerparticles are placed in at least one of the strata of the upper ply inlongitudinal discrete lanes along the length of the core, said lanesincluding from about 70% to 100% superabsorbent polymer particles, andsaid lanes being separated by adjacent lanes including fibers and abinder.
 24. The structure of claim 1 wherein superabsorbent polymerparticles are placed in the lower ply in longitudinal discrete lanesalong the length of the core, said lanes including from about 70% to100% superabsorbent polymer particles, and said lanes being separated byadjacent lanes including fibers and a binder.
 25. An absorbent structurehaving wet integrity higher than about 4.0 kN/gsm, softness higher than8.0/J, pliability higher than about 70/N, and providing a substantiallydry liquid-accepting surface after receiving a quantity of liquid, thesaid structure comprising: a) an upper ply having an upper fluidreceiving surface and a lower surface comprising: i) a top stratumincluding synthetic matrix fibers bonded with a binder, said matrixfibers having length of from about 2 to about 15 mm; ii) a middlestratum in fluid communication with the top stratum, the middle stratumincluding natural fibers and superabsorbent polymer particles; and iii)a bottom stratum in fluid communication with the middle stratum,including natural fibers and a binder; b) and a lower ply in fluidcommunication with the upper ply, the lower ply having an upper surfaceand a lower surface and including: i) a top stratum including naturalfibers and a binder; and ii) a bottom stratum including natural fibers,superabsorbent polymer particles, and a binder, wherein: a) the lowersurface of the upper ply has a surface area less than about 80% of theupper surface area of the lower ply; b) the top stratum of the upper plyexhibits essentially no fluid wicking capability; c) the basis weight ofthe top stratum of the upper ply is from about 20 gsm to about 120 gsm;d) the binder content (percent by weight) of the top stratum of theupper ply is from about 5% to about 20%; e) the basis weight of themiddle stratum of the upper ply is from about 50 gsm to about 1000 gsm;f) the binder content (percent by weight) of the middle stratum of theupper ply is from about 1% to about 10%; g) the basis weight of thebottom stratum of the upper ply is from about 10 gsm to about 150 gsm;h) the binder content (percent by weight) of the bottom stratum of theupper ply is from about 5% to about 15%; i) the content ofsuperabsorbent particles in the upper ply is lower than the content ofsuperabsorbent particles in the lower ply; j) the lower ply contains atleast 30% superabsorbent particles based on the total basis weight ofthe lower ply; k) the top stratum of the lower ply contains from about0% to about 20% superabsorbent particles based on the basis weight ofthe top stratum of the lower ply; l) the basis weight of the lower plyis from about 100 gsm to about 1000 gsm; m) the apparent density of thelower ply is about 0.15 g/cc to about 0.25 g/cc; n) the apparent densityof the upper ply is lower than the apparent density of the lower ply;and o) the binder content (percent by weight) of the lower ply is fromabout 1% to about 8%.
 26. The absorbent structure of claim 25 whereinthe length of the synthetic matrix fibers is from about 4 to about 12mm.
 27. The absorbent structure of claim 25 wherein the synthetic matrixfibers are from about 2 to about 30 denier.
 28. The absorbent structureof claim 27 wherein the synthetic matrix fibers are from about 6 toabout 15 denier.
 29. The absorbent structure of claim 25 wherein thesynthetic matrix fibers are selected from the group consisting ofpolyethylene, polypropylene, polyester, polyamide, cellulose acetate,rayon, and mixtures thereof.
 30. The absorbent structure of claim 25wherein the binder is selected from the group consisting of latexbinders, thermoplastic powders, thermoplastic fibers, bicomponent fibersand mixtures thereof.
 31. The absorbent structure of claim 25 whereinthe binder is a water-soluble or water-dispersable bonding polymeragent.
 32. The absorbent structure of claim 25 wherein the naturalfibers are selected from the group consisting of cotton, softwood pulp,hardwood pulp, straw, keaf fibers, cellulose fibers modified bychemical, mechanical and/or thermal treatments, keratin and mixturesthereof.
 33. The absorbent structure of claim 25 wherein the basisweight of the top stratum of the upper ply is from about 30 gsm to about60 gsm.
 34. The absorbent structure of claim 25 wherein the content ofsynthetic matrix fibers in the top stratum of the upper ply is fromabout 50 to about 99% by weight.
 35. The absorbent structure of claim 25wherein the content of synthetic matrix fibers in the top stratum of theupper ply is from about 75 to about 90% by weight.
 36. The absorbentstructure of claim 25 wherein the basis weight of the middle stratum ofthe upper ply is from about 80 gsm to about 300 gsm.
 37. The absorbentstructure of claim 25 wherein the content of superabsorbent polymerparticles in the middle stratum of the upper ply is from about 5 toabout 60% by weight of the upper ply.
 38. The absorbent structure ofclaim 25 wherein the content of superabsorbent polymer particles in themiddle stratum of the upper ply is from about 20 to about 50% by weightof the upper ply.
 39. The absorbent structure of claim 25 wherein thebasis weight of the lower ply is from about 150 gsm to about 400 gsm.40. The absorbent structure of claim 25 wherein the overall content ofsuperabsorbent polymer particles in the lower ply is from about 30 toabout 80% by weight.
 41. The absorbent structure of claim 25 wherein thecontent of superabsorbent polymer particles in the lower ply is fromabout 40 to about 60% by weight.
 42. The absorbent structure of claim 25wherein the bottom stratum of the upper ply is airlaid.
 43. Theabsorbent structure of claim 25 wherein the bottom stratum of the upperply is a wet-laid cellulose tissue.
 44. The absorbent structure of claim25 wherein the basis weight of the top stratum of the lower ply is fromabout 10 gsm to about 150 gsm.
 45. The absorbent structure of claim 25wherein the basis weight of the top stratum of the lower ply is fromabout 15 gsm to about 90 gsm.
 46. The absorbent structure of claim 25wherein all strata in each ply are fully integrated in the formingprocess.
 47. The structure of claim 25 made by airlaid process.
 48. Thestructure of claim 25 wherein superabsorbent polymer particles areplaced in at least one of the strata of the upper ply in longitudinaldiscrete lanes along the length of the core, said lanes including fromabout 70% to 100% superabsorbent polymer particles, and said lanes beingseparated by adjacent lanes including fibers and a binder.
 49. Thestructure of claim 25 wherein superabsorbent polymer particles areplaced in at least in one stratum of the lower ply in longitudinaldiscrete lanes along the length of the core, said lanes including fromabout 70% to 100% superabsorbent polymer particles, and said lanes beingseparated by adjacent lanes including fibers and a binder.
 50. Anabsorbent structure comprising: a) an upper ply including: i) a topstratum including polyester matrix fibers bonded with latex in an amountof 15 to 25% by weight of said top stratum, said matrix fibers havinglength from about 4 mm to about 8 mm and having thickness from about 9to about 15 denier per fiber, the basis weight of said top stratum beingfrom about 40 to about 60 gsm; ii) a middle stratum in fluidcommunication with the top stratum, the middle stratum includingsoftwood fluff, superabsorbent polymer particles, and binder fiber, thecontent of the superabsorbent polymer particles being from about 30 to40% of the basis weight of the said middle stratum, the content of thebinder fibers being from about 6 to about 12% of the basis weight of thesaid middle stratum, and the basis weight of the said middle stratumbeing from about 150 to about 200 gsm; iii) a bottom stratum in fluidcommunication with the middle stratum, including softwood fluff andbinder fibers, the content of the binder fibers being from about 8 toabout 16% of the basis weight of the said bottom stratum, and the basisweight of the said bottom stratum being from about 60 to about 120 gsm;and b) a lower ply in fluid communication with the upper ply, the lowerply comprising: i) a top stratum including softwood fluff and binderfibers, the content of the binder fibers being from about 10 to about25% of the basis weight of the said top stratum, and basis weight beingfrom about 20 to about 60 gsm; ii) a bottom stratum including softwoodfluff, superabsorbent polymer particles, and binder fibers, the contentof the superabsorbent polymer particles being from about 50 to about 80%of the basis weight of the said bottom stratum, the content of thebinder fibers being from about 2 to 5% of the basis weight of the saidbottom stratum; and iii) cellulose tissue upon which the lower ply hasbeen formed, wherein: a) the upper ply has a surface area adjacent tothe lower ply, said surface area being from about 40 to 60% of thefacing surface area of the lower ply; b) the density of the upper ply isfrom about 0.05 to about 1.0 g/cc; c) the density of the lower ply isfrom about 0.15 to about 0.3 g/cc.
 51. An absorbent structurecomprising: a) an upper ply containing: i) a top stratum includingpolyester matrix fibers bonded with latex in an amount of 15 to 25% byweight of said top stratum, said matrix fibers having length from about4 mm to about 8 mm and having thickness from about 9 to about 15 denierper fiber, the basis weight of said top stratum being from about 40 toabout 60 gsm; ii) a middle stratum in fluid communication with the topstratum, the middle stratum including softwood fluff, superabsorbentpolymer particles, and binder fiber, the content of the superabsorbentpolymer particles being from about 40 to 60% of the basis weight of thesaid middle stratum, the content of the binder fibers being from about 6to about 12% of the basis weight of the said middle stratum, and thebasis weight of the said middle stratum being from about 200 to about280 gsm; iii) a bottom stratum in fluid communication with the middlestratum, including softwood fluff and binder fibers, the content of thebinder fibers being from about 8 to about 16% of the basis weight of thesaid bottom stratum, and the basis weight of the said bottom stratumbeing from about 60 to about 120 gsm; and b) a lower ply in fluidcommunication with the upper ply, the lower ply comprising: i) a topstratum including softwood fluff and binder fibers, the content of thebinder fibers being from about 10 to about 25% of the basis weight ofthe said top stratum, and basis weight being from about 20 to about 60gsm; ii) a bottom stratum including softwood fluff, superabsorbentpolymer particles, and binder fibers, the content of the superabsorbentpolymer particles being from about 40 to about 60% of the basis weightof the said bottom stratum, the content of the binder fibers being fromabout 2 to 5% of the basis weight of the said bottom stratum, and thebasis weight of the said bottom stratum being from about 200 to about350 gsm; and iii) cellulose tissue upon which the lower ply has beenformed, wherein: c) the upper ply has a surface area adjacent to thelower ply, said surface area being from about 40 to 60% of the facingsurface area of the lower ply; d) the density of the upper ply is fromabout 0.05 to about 1.0 g/cc; e) the density of the lower ply is fromabout 0.15 to about 0.3 g/cc.
 52. An absorbent article for absorbingbody fluids, comprising the absorbent structure of claim 1 sandwichedbetween a liquid pervious top sheet and liquid impervious backsheet. 53.An absorbent article for absorbing body fluids, comprising the absorbentstructure of claim 25 sandwiched between a liquid pervious topsheet andliquid impervious backsheet.
 54. An absorbent article for absorbing bodyfluids, comprising the absorbent structure of claim 50 sandwichedbetween a liquid pervious topsheet and liquid impervious backsheet. 55.An absorbent article for absorbing body fluids, comprising the absorbentstructure of claim 51 sandwiched between a liquid pervious topsheet andliquid impervious backsheet.
 56. An absorbent structure having wetintegrity higher than about 4.0 kN/gsm, softness higher than 8.0/J,pliability higher than about 70/N, and providing a substantially dryliquid-accepting surface after receiving a quantity of liquid, saidstructure comprising: a) an upper ply having an upper fluid receivingsurface and a lower surface and comprising: i) a top stratum comprisingsynthetic matrix fibers bonded with a binder, said matrix fibers havinglength from about 2 to about 15 mm; ii) a middle stratum in fluidcommunication with the top stratum, the middle stratum including naturalfibers, superabsorbent particles and a binder; and iii) a bottom stratumin fluid communication with the middle stratum, the bottom stratumincluding natural fibers and a binder; and b) a lower ply in fluidcommunication with the upper ply, the lower ply having an upper surfaceand a lower surface and including at least one stratum including naturalfibers, superabsorbent polymer particles, and a binder, wherein thelower surface of the upper ply has a surface area less than about 80% ofthe upper surface area of the lower ply.
 57. An absorbent structurehaving wet integrity higher than about 6.0 kN/gsm, softness higher than8.0/J, pliability higher than about 70/N, and providing a substantiallydry liquid-accepting surface after receiving a quantity of liquid, saidstructure comprising: c) a top stratum comprising synthetic matrixfibers bonded with a binder, said matrix fibers having length from about2 to about 15 mm; d) a middle stratum in fluid communication with thetop stratum, the middle stratum comprising natural fibers,superabsorbent polymer particles and a binder; and e) a bottom stratumin fluid communication with the middle stratum, comprising naturalfibers and a binder.
 58. The absorbent structure of claim 57 wherein thesynthetic matrix fibers are from about 2 to about 30 denier per fiber.59. The absorbent structure of claim 58 wherein the synthetic matrixfibers are from about 6 to about 15 denier per fiber.
 60. The absorbentstructure of claim 57 wherein the synthetic matrix fiber is selectedfrom the group consisting of polyethylene, polypropylene, polyester,polyamide, cellulose acetate, rayon fibers and mixtures thereof.
 61. Theabsorbent structure of claim 57 wherein the binder is selected from thegroup consisting of latex binders, thermoplastic powders, thermoplasticfibers, bicomponent fibers and mixtures thereof.
 62. The absorbentstructure of claim 57 wherein the binder is selected from the groupconsising of polyamide-polyamine epichlorohydrine adducts, cationicstarch, dialdehyde starch, poly(vinyl alcohol), chitosan and mixturesthereof.
 63. The absorbent structure of claim 57 wherein the naturalfibers are selected from the group consisting of cotton, softwood pulps,hardwood pulps, straw, keaf fibers, cellulose fibers modified bychemical, mechanical and/or thermal treatments, keratin fibers andmixtures thereof.
 64. The absorbent structure of claim 57 wherein thebasis weight of the top stratum is from about 20 gsm to about 120 gsm.65. The absorbent structure of claim 64 wherein the basis weight of thetop stratum is from about 30 gsm to about 60 gsm.
 66. The absorbentstructure of claim 57 wherein the content of synthetic matrix fibers inthe top stratum is from about 50 to about 99% by weight.
 67. Theabsorbent structure of claim 66 wherein the content of synthetic matrixfibers in the top stratum is from about 75 to about 90% by weight. 68.The absorbent structure of claim 57 wherein the basis weight of themiddle stratum is from about 50 gsm to about 1000 gsm.
 69. The absorbentstructure of claim 68 wherein the basis weight of the middle stratum ofthe upper ply is from about 80 gsm to about 300 gsm.
 70. The absorbentstructure of claim 57 wherein the content of superabsorbent polymerparticles in the middle stratum is from about 5 to about 60% by weightof the absorbent structure.
 71. The absorbent structure of claim 70wherein the content of superabsorbent polymer particles in the middlestratum is from about 20 to about 50% by weight.
 72. The absorbentstructure of claim 57 wherein the bottom stratum is an airlaid layer.73. The absorbent structure of claim 57 wherein the bottom stratum is awet-laid cellulose tissue.
 74. The absorbent structure of claim 57wherein all strata of the said structure are fully integrated in theforming process.
 75. The absorbent structure of claim 57 made by airlaidprocess.
 76. The structure of claim 57 wherein superabsorbent polymerparticles are placed at least in one of the strata in longitudinaldiscrete lanes along the length of the core, said lanes including fromabout 70% to 100% superabsorbent polymer particles, and said lanes beingseparated by adjacent lanes including fibers and a binder.
 77. Anabsorbent structure, comprising: i. a top stratum comprising polyesterfibers bonded with latex in an amount of 15 to 25% by weight of said topstratum, said matrix fibers having length from about 4 mm to about 8 mmand having thickness from about 9 to about 15 denier per fiber, thebasis weight of said top stratum being from about 40 to about 60 gsm;iii. a middle stratum in fluid communication with the top stratum, themiddle stratum comprising softwood fluff fiber, superabsorbent polymerparticles, and binder fiber, the content of the superabsorbent polymerparticles being from about 30 to 40% of the basis weight of the saidmiddle stratum, the content of the binder fibers being from about 6 toabout 12% of the basis weight of the said middle stratum, and the basisweight of the said middle stratum being from about 150 to about 200 gsm;and iii. a bottom stratum in fluid communication with the middlestratum, comprising softwood fluff and binder fibers, the content of thebinder fibers being from about 8 to about 16% of the basis weight of thesaid bottom stratum, and the basis weight of the said bottom stratumbeing from about 60 to about 120 gsm, wherein the density of thestructure is from about 0.05 to about 0.3 g/cc, and the structure has awet integrity higher than about 6.0 kN/gsm, softness higher than 8.0/Jand pliability higher than about 70/N.
 78. An absorbent structurestructure, comprising: i. a top stratum comprising polyester matrixfibers bonded with latex in an amount of 15 to 25% by weight of said topstratum, said matrix fibers having length from about 4 mm to about 8 mmand having thickness from about 9 to about 15 denier per fiber, thebasis weight of said top stratum being from about 40 to about 60 gsm;ii. a middle stratum in fluid communication with the top stratum, themiddle stratum comprising softwood fluff fiber, superabsorbent polymerparticles, and binder fiber, the content of the superabsorbent polymerparticles being from about 40 to 60% of the basis weight of the saidmiddle stratum, the content of the binder fibers being from about 6 toabout 12% of the basis weight of the said middle stratum, and the basisweight of the said middle stratum being from about 200 to about 280 gsm;and iii. a bottom stratum in fluid communication with the middlestratum, comprising softwood fluff and binder fibers, the content of thebinder fibers being from about 8 to about 16% of the basis weight of thesaid bottom stratum, and the basis weight of the said bottom stratumbeing from about 60 to about 120 gsm, wherein the density of the saidstructure is from about 0.05 to about 1.0 g/cc, and the structure has awet integrity higher than about 6.0 kN/gsm, softness higher than 8.0/Jand pliability higher than about 70/N.
 79. An absorbent article forabsorbing body fluids, comprising the absorbent structure of claim 57sandwiched between a liquid pervious topsheet and liquid imperviousbacksheet.